Aircraft wake vortices: a comparison of wind-tunnel data with field trial measurements by laser radar

A method is presented for comparison of measurements on aircraft wake vortices obtained using two very different techniques: 1) five-hole probe measurements on a 1/13.6 (7.35%) scale half-model of an Airbus A321 were made in a wind tunnel, and 2) coherent laser radar (lidar) measurements were made in full-scale field trials at Toulouse Blagnac Airport. The lidar measurements provide line-of-sight tangent velocities across the vortex pair to over half the peak core velocity, whereas the wind tunnel measurements cover the full core region, extending nearly to the mid point. Measurements from the two systems may thus be compared over the overlap region of the vortex profile. Over this range the measured tangent velocity profiles show good agreement for vortices of comparable age. Vortex disturbance is brought about by atmospheric turbulence, and the effects are evident in the lidar data, leading to significant distortion of older vortices. Some implications of the results are discussed together with points of comparison for the two measurement systems. The complementary character of the information that may be derived from the two techniques is emphasised. (C) 2000 Editions scientifiques et medicales Elsevier SAS.